package Translation;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
import java.util.HashMap;
import java.util.Map;

public class UdpTranslateServer {
    private DatagramSocket socket = null;
    private Map<String,String> map = new HashMap<>();

    public UdpTranslateServer(int port) throws SocketException {
        this.socket = new DatagramSocket(port);
        map.put("translate","翻译");
        map.put("china","中国");
        map.put("hello","你好");
    }

    public void start() throws IOException {
        System.out.println("服务器启动!");
        while (true) {
            // 1. 读取请求并解析
            DatagramPacket requestPacket = new DatagramPacket(new byte[4096],4096);
            socket.receive(requestPacket);
            String request = new String(requestPacket.getData(),0, requestPacket.getLength());
            // 2. 根据请求计算响应
            String response = process(request);
            // 3. 把响应写回给客户端
            DatagramPacket responsePacket = new DatagramPacket(response.getBytes(),response.getBytes().length,
                                                                requestPacket.getSocketAddress());
            socket.send(responsePacket);
            // 4. 打印日志
            String log = String.format("[%s:%d] req: %s; resp: %s",requestPacket.getAddress().toString(),
                                        requestPacket.getPort(),request,response);
            System.out.println(log);
        }
    }

    private String process(String request) {
        return map.getOrDefault(request,"查无此单词");
    }

    public static void main(String[] args) throws IOException {
        UdpTranslateServer server = new UdpTranslateServer(9090);
        server.start();
    }
}
